Calibrating Ha Flats

I have just received my new Baader 36mm LRGB & Ha(7nm) filters. My 1.25" Baader Ha(35nm) would calibrate along with the rest of the LRGB filters. But because of the new Ha 7nm filter, I cannot achieve calibration. The max timing allowed in the wizard is 100 seconds. All my other 36mm filters will calibrate well within 30 seconds. Bear in mind that I am using 2 sheets of white card stock. I am using a Gerd Neumann light panel.

I could remove the card stock and do an Ha calibration and it would probably take, but if I go to save that single Ha calibration into my existing profile, it will wipe my LRGB calibrations for that profile. I don’t think an equipment profile can have two calibrations. Can it? Do I really need to take Ha flats?

Thanks in advance


I am not sure what this means. We don’t impose any limits like this. Maybe you are confusing the “Minimum exposure field” with the max timing? Not sure… Minimum times are only to prevent mechanical shutters from introducing bad gradients in very fast exposures.

Not for the same filter, but if you uncheck the LRGB filters in the flats wizard it will only get data for Ha and only save Ha data (it will not (should not) overwrite your LRGB data… if it does it’s a bug).

Thanks Ken,

I didn’t realize that you could go about doing separate filter calibrations,
and that as long as they weren’t the same filter,

it would update the profile without wiping out the profile. Great!!

Now, the timing thing…In understand the minimum allowable exposure length
as I have an ATIK 383L with a mechanical shutter.

The other box…“Maximum Exposure”…Can you explain a little further. I
understood it to be a set “ceiling” or timing in seconds

for an exposure with a maximum entry of 100 seconds but I am wrong.

Thanks again Ken

That is correct. The max exposure field is meant to protect insanely high exposure times for inadequate light sources. That said, the max field is allowed up tp 1200 seconds (20 min). That is why I mentioned you might have confused it with the min filed which does have a cap of 100 sec. Using the max exposure field, the Flats Cal Wizard will fail (and move to the next filter), if it requires an exposure greater than this time.